Charmed Tetraquarks Tcc and Tcs from Dynamical Lattice QCD Simulations

Abstract

Charmed tetraquarks $T_{cc}=(cc\bar{u}\bar{d})$ and $T_{cs}=(cs\bar{u}\bar{d})$ are studied through the S-wave meson-meson interactions, $D$-$D$, $\bar{K}$-$D$, $D$-$D^{\ast }$ and $\bar{K}$-$D^{\ast }$, on the basis of the (2+1)-flavor lattice QCD simulations with the pion mass $m_{\pi }\simeq$410, 570 and 700 MeV. For the charm quark, the relativistic heavy quark action is employed to treat its dynamics on the lattice. Using the HAL QCD method, we extract the S-wave potentials in lattice QCD simulations, from which the meson-meson scattering phase shifts are calculated. The phase shifts in the isospin triplet ($I$=1) channels indicate repulsive interactions, while those in the $I=0$ channels suggest attraction, growing as $m_{\pi }$ decreases. This is particularly prominent in the $T_{cc}(J^P=1^{+},I=0)$ channel, though neither bound state nor resonance are found in the range $m_{\pi }=410-700$ MeV. We make a qualitative comparison of our results with the phenomenological diquark picture.

Comments: 15 pages, 4 figures